It is well known that interconnection of a plurality of computers on a network realizes information resource sharing, hardware resource sharing and an inter-user collaboration. Inter-computer connection media are available in various types such as LAN (Local Area Network), WAN (Wide Area Network) and Internet etc.
In particular, computer and network technologies etc. are recently being widespread among general homes. Home information apparatuses such as personal computers and PDAs (Personal Digital Assistants), and besides, various types of informative home information appliances such as televisions and video players are interconnected via a home network.
In most cases, the home network is interconnected via a router to an external wide area network, typically the Internet. For instance, after content having been rightfully acquired from a server on the Internet is stored in a server (which is hereinafter also referred to as “a home server”) on the home network, the content is distributed to other home terminals (clients) via the home network, thereby enabling the same content to be enjoyed within the home.
Nowadays, UPnP™ is known as a protocol constituting the home network, for instance. According to the UPnP™, a network may be easily established without involving any complicated operation, thereby enabling a content distribution service to be provided between networked apparatuses without involving any troublesome operation or setting. Further, the UPnP™ has an advantage of being non-dependent on an operating system (OS) so that more apparatuses may be easily networked.
In the UPnP™, a mutual authentication takes place between the networked apparatuses through an exchange of a definition file described in the form of XML (eXtensible Markup Language). An outline of UPnP™ processing is as follows.
(1) Addressing: Processing to acquire one's own device ID such as an IP address.
(2) Discovery: Processing to effect a retrieval of each device on the network for acquiring information regarding device types and functions etc. contained in a response having been received from each device.
(3) Service request: Processing to give a service request to each device on the basis of the information having been acquired by the discovery processing.
A practice to follow a procedure of the above processing may result in distribution and reception of the service to which the networked apparatuses are applied. A newly networked apparatus acquires the device ID through the addressing processing to acquire information of another networked device through the discovery processing, so that the service request may be available.
Other apparatuses on the home network may have access to the content stored in the home server. Then, the apparatuses having established a UPnP™ connection may acquire the content from the home server. In a case where the content is video data or audio data, a connection to the TV or the player etc. as the apparatus connected to the network may result in watching of movies or listening to the music.
On the other hand, content handled via the network is in the form of digital data, in which case, a problem arises that unauthorized operations such as copying and falsifying are put into practice relatively with ease. At present days, fraudulent acts such as copying and falsifying of the contents frequently take place, which contribute to a primary factor of an obstruction to profits of digital content venders. This also brings about a need for a raise in content price, resulting in an occurrence of a vicious cycle supposed to constitute a barrier to a more widespread use.
Under the Copyright Law, the digital contents are protected as one of literary works against unfair uses such as unauthorized duplication and falsifying. It is stipulated in Section 30 of the Copyright Law, for instance, that as far as a purpose of private or home use etc., a user oneself might be authorized to duplicate the literary works without restrictions on a type of literary works or a mode of duplication. Further, Sub-Section 1 of Section 49 of the Copyright Law provides to the effect that a transfer of a duplication right of a copyright owner arises in the case where a duplicated matter having been created for the private use was applied for a purpose other than the private use, that is, prohibits what is called a use in excess of the purpose of private use.
In a case of introducing a concept of the private use into the home network, the client terminals connected to the home network are supposed to fall within the range of private or home use. Thus, the client terminals on the home network are deemed to be adaptable to freely use the rightfully acquired contents in the home server. As a matter of course, it is necessary to put certain restrictions on the number of terminals that enable the content to be given. The DTCP (Digital Transmission Control Protection) specified as an industry standard that defines a digital transmission content protection imposes restrictions on a communication area in which contents are transmitted and the number of apparatuses allowed to receive the contents (Refer to a non-patent document 1, for instance).
However, any technologies under the present conditions have difficulty in determining that the client terminal having finished a login to the home network falls within the range of private use or not.
For instance, since the home network is interconnected to the external network through the router on a protocol basis, an actual current position of the client having gained access is unknown to the home server. If the home server distributes the content in response to an external (remote) access, the content is subject to an approximately unrestricted utilization, in which case, a copyright on the content is supposed to have almost no protection. As a result, there is a fear that a content creator will lose one's inspiration for creation.
On the other hand, if strict restrictions are imposed on the client terminals, the user fails to secure the private use supposed to be authorized essentially under the provisions of the Copyright Law. As a result, the user cannot fully enjoy the content, which leads to a failure in progress of the utilization of the home server and a content distribution service, so that there is a fear that a hindrance to a content business development itself will arise.
In view of circumstances that the user who is a rightful purchaser of the literary works is authorized to utilize the literary works at will, there is provided a proposal on a method ensuring that an acceptance of a content right holder is easily obtained in a case where the user makes the duplication of information on the network into the utilization (Refer to a Patent document 1, for instance). However, this method is to classify the users depending on a level of relation with an information utilization-right holder, before distributing the information according to distribution ways being different for each relation level, but not to determine to what extent on the network is applicable to the range of private use.
Further, as one method of rejecting unauthorized access of the external network to the home network, a method of allowing the home server to hold a list of access authorized clients may be taken to reject the unauthorized access by performing a collation with the list every time an access request from the client to the home server is caused.
For instance, there is known a MAC (Media Access Control) address filtering that provides a list given as an access authorized apparatus list using a MAC address specified as a physical address that is unique to each communication apparatus. That is, following a preliminary registration of the MAC address of each access authorized apparatus in a router or a gateway serving to isolate an internal network like the home network from the external network, the MAC address assigned to a received packet is collated with the registered MAC address, whereby any access by the apparatus having an unregistered MAC address is rejected (Refer to a patent document 2, for instance).
However, it is necessary to check the MAC addresses of all the apparatuses connected to the internal network in order to build an access authorized apparatus list, and besides, much labor is taken to create the list by an entry of all the acquired MAC addresses. Further, in the home network, the connected apparatuses are subject to relatively frequent changes, resulting in a need to update the access authorized apparatus list for each of the above changes.
In a case where the home network is indirectly connected to the external network through the router or the gateway, it is allowable to determine, on the basis of the MAC address etc., that the client is connected to which of the home network or the external network. Conversely, in a case where the home network is directly connected to the external network by a modem etc., it is difficult or impossible to identify that the client is connected to which of the home network or the external network.
[Patent Document 1]
Published Japanese Patent Application (KOKAI) No. 2002-73861
[Patent Document 2]
Published Japanese Patent Application (KOKAI) No. Hei 10-271154
[Non-Patent Document 1]
http://www.dtcp.com/data/info 20031124 dtcp Vol 1 1p3.pdf